Is this load of wood to heavy for the wall?

[keith ouellette]

I have been asked to ask all of you if this is to heavy for my lumber rack.

The wall is a 2x4 frame made with 10' studs and a double top plate. The wall is anchored to the slab with 8" bolts (set in the concrete) and has hurricane strapping at the top and bottom of each stud. The outside is sheathed with 5/8 plywood and the inside is sheathed with 1/2" osb. The racks are secured with 3"x3/8 lag bolts. 3 on each rack (top bottom and middle).

Someone thinks its going to fall on me so I agreed to get some educated opinions to be safe.

111291

[Kevin Groenke]

I don't think it's too heavy for the wall, but it might be pushing the limits of the shelf brackets.

[Scott Wigginton]

I say yes but I'm no structural engineer.

One way to beef it up to make the old lady feel better is to extend the rear rails to the slab. This will then bear the vertical load and the walls will only have the shear stress.

Hopefully someone with some authority in structural loads can chime in.

[Scott Wigginton]

I don't think it's too heavy for the wall, but it might be pushing the limits of the shelf brackets.

I believe the ones he is using is rated at 300 lbs at the tip (or 600 lbs evenly distributed), doesn't look like he has half a ton on any pair of brackets (he has several tiers, hard to see 'cause of how crammed in it is)

[keith ouellette]

I don't think it's too heavy for the wall, but it might be pushing the limits of the shelf brackets.

The shelf brackets are pretty thick. I think they are the ones from shop fox.

[John Shuk]

Those shelf brackets are the exact same type we use in manholes for holding communications cables. They are extremely strong. In any given manhole they are holding multiple lead sheathed cables that are very very heavy. I wouldn't be too concerned about overloading the brackets.
Can't speak to the wall though.

[keith ouellette]

I say yes but I'm no structural engineer.

One way to beef it up to make the old lady feel better is to extend the rear rails to the slab. This will then bear the vertical load and the walls will only have the shear stress.

Hopefully someone with some authority in structural loads can chime in.

Would cramming a 2x4 between the bottom of the rack and the floor and then screwing it to the stud do what you are suggesting.

[Dennis Ford]

I have about the same amount on a similar wall, I feel OK with the load on the wall but have to very careful when removing a board. Watch out for overloaded brackets!

[Peter Gregory]

I have at least twice and maybe three times that much wood on my wall. If you have a problem, guess I'm really hosed. :)

[John Keeton]

I would not be uncomfortable with that situation at all. But, just tell that someone you don't plan to sit down under the load or take a nap under it!

[Mark Bolton]

Custom home builder here. I would be more worried about the standards, brackets, and fasteners. You will likely never have an effect on the wall even if you installed standards to the floor and filled the entire wall with lumber. The standards/brackets/fasteners will fail before the wall does.

One thing to remember is that shelving systems are normally rated in two ways. First is what the standards max capacity is, then what the brackets will handle. A system is normally rated based on a given standard spacing then the brackets are rated for their individual load carrying capabilities.

So given the standards handle it, if the brackets are rated at 600lbs evenly distributed (as another post said) 6 of brackets would handle 3600lbs. With white oak weighing about 4k/mbf at 20% that would be hard to hit with your setup.

Mark

[Jack Ellis]

I'm not a structural engineer either but it looks OK. I'm going to have 24" shelves bolted into a 2x4 wall for lumber in my new shop and I've convinced myself it'll be OK, especially after they stiffened the studs (furring) so they would not bend so easily.

I'm puzzled, though, because it appears you have an outside wall that's wood frame. I thought all homes in hurricane country used concrete block with furring inside? I used to live near Cocoa Beach and I don't remember any wood frame outside walls, though we're talking 30+ years ago and my memory ain't what it used to be.

[keith ouellette]

I'm not a structural engineer either but it looks OK. I'm going to have 24" shelves bolted into a 2x4 wall for lumber in my new shop and I've convinced myself it'll be OK, especially after they stiffened the studs (furring) so they would not bend so easily.

I'm puzzled, though, because it appears you have an outside wall that's wood frame. I thought all homes in hurricane country used concrete block with furring inside? I used to live near Cocoa Beach and I don't remember any wood frame outside walls, though we're talking 30+ years ago and my memory ain't what it used to be.

Thanks for all the replies.

Jack; we have a number of wood frame homes around here. They are well within code though the codes for frame construction got beefed up quite a bit after hurricane andrew hit further south.

That being said the workshop is not part of the house (the house is block) but is more like a detached garage. There are many frame homes in cocoa but I bet in cocoa beach where people had more money the homes were all block.

[george wilson]

I have a huge load of wood inside my wall. I made the lumber rack out of 2 1/2" heavy gauge angle iron that goes clear to the floor. There is a angle sticking out right on the floor 2' wide,same as on the brackets above. This transfers the load to the floor,rather than to the walls. I figured out that with a 50-50 load of spruce and hard maple,there could be a 4000# load on those brackets,which made me nervous. Hence,transfering the load to the floor.

[keith ouellette]

I have a huge load of wood inside my wall. I made the lumber rack out of 2 1/2" heavy gauge angle iron that goes clear to the floor. There is a angle sticking out right on the floor 2' wide,same as on the brackets above. This transfers the load to the floor,rather than to the walls. I figured out that with a 50-50 load of spruce and hard maple,there could be a 4000# load on those brackets,which made me nervous. Hence,transfering the load to the floor.

2 1/2" angle iron. when you build you really build. I see what you are saying though. I originally, when I put it up a couple of years ago, that the load would be spread out over the whole system meaning if there was 3 or 4 thousand pounds on the whole thing each rail and bracket would only have to handle a portion of the load.

I like your design better though.

[Chris Bruno]

Hi Keith,

I'm a mechanical engineer (if that means anything) and I think your walls and your brackets appear like they will not have any trouble... the only thing I'd be worried about is only having (3) 3x3/8" lag bolt per standard.

Can you estimate the weight of one of those boards? Its a relatively easy calculation to see if you need to worry much about the bolts... shear is probably not a concern (pull-out is probably more likely), but it never hurts to run the numbers to check...

-Chris

[Kevin Godshall]

Hi Keith,

I'm a mechanical engineer (if that means anything) and I think your walls and your brackets appear like they will not have any trouble... the only thing I'd be worried about is only having (3) 3x3/8" lag bolt per standard.

Can you estimate the weight of one of those boards? Its a relatively easy calculation to see if you need to worry much about the bolts... shear is probably not a concern (pull-out is probably more likely), but it never hurts to run the numbers to check...

-Chris

+1 on Chris' input. All things considered, most of the time when things fail, it's not because of the brackets or the wall structure (main supports), it's because the fasteners (holding devices) were undersized or insufficient, and they fail, causing the rest to fail.

Your only as strong as your weakest link.

[Lee Schierer]

+1 on Chris' input. All things considered, most of the time when things fail, it's not because of the brackets or the wall structure (main supports), it's because the fasteners (holding devices) were undersized or insufficient, and they fail, causing the rest to fail.

Your only as strong as your weakest link.

I'm in agreement with the question on the fasteners. Conventional lag screws are not very strong. If it were my lumber rack I would attach it to the wall using the Timber Lock Screws http://www.castlewholesalers.com/media/43472030, which have a greater tensile and pull out strength and are much less likely to fail. Oh, wait, I did attach my lumber rack to the wall with Timber Lock screws

The other thing that I would think about is how is that wall anchored at the top? You have a lot of weight on one side and if the wall is not tied into the structure above it may lean.

[keith ouellette]

I'm in agreement with the question on the fasteners. Conventional lag screws are not very strong. If it were my lumber rack I would attach it to the wall using the Timber Lock Screws http://www.castlewholesalers.com/media/43472030, which have a greater tensile and pull out strength and are much less likely to fail. Oh, wait, I did attach my lumber rack to the wall with Timber Lock screws

The other thing that I would think about is how is that wall anchored at the top? You have a lot of weight on one side and if the wall is not tied into the structure above it may lean.

The wall has a double top plate as well as an osb sheathed ceiling and the ply wood floor running down the center of the attic. Plus it has a brace on the gable end truss to tie in to an inner truss. Not to mention the wall is actually bolted to the slab about every 30". each stud has strapping that goes underneath and 6" up each side of every stud and the same thing is on top so the sole and top plate are tied in to the studs very strongly.

Now that I think about it I let my wife worry me for nothing (big surprise) about the wall. Like others have said I think the lag bolts may be an issue.

Thanks for all the input.

[Brian Effinger]

Keith - I'm an architect and only dabble in structural engineering. I could use a little more information before I offer my 2 cents.
1. what is sitting on top of this wall - roof and ceiling or a floor?
2. Which way does the structure above run - perpendicular to this wall or parallel?
3. How thick are these shelf standards? What I mean by that is how much steel does the lag screw have to go through to get into the framing, which reduces the effective length of the lag.

As you said above, the lag screws may be the weak link here, because the wall should be able to handle this load, especially with sheathing on each side. That being said, usually when I design a house with walls over 8 or 9 feet high, I switch to 2x6 studs, especially if it is load bearing or an exterior wall. From memory, lags of this size are rated at about 200# in shear (maybe a little less?), so if you have 3 per bracket, you are good for 600#, but that is if all 3" are in the wall. I cannot recall what the pull-out strength is though. This number depends on the screw itself, as well as the species of lumber it is in (SYP is better than SPF for example).

I took a look at my Simpson Strong-tie book, and their SDS wood screws (probably similar to Lee's timber locks) are what you would use here. If you were to use 1/4"x3" screws, and the studs were a southern species, you would have 470# shear strength and 345# in withdrawal per screw. Now if you only had 2 1/2" engaged in the wood, the withdrawal would be reduced to #259 per screw. I have attached the catalog page for these screws.

Hopefully I have made sense here. If not you please feel free to tell me I'm nuts. :)

Brian

[Thomas Canfield]

The one item that was not addressed is the type of bolting or screws used to mount the brackets. That will most likely be the weak link in the system. There is the problem of getting enough screw engagement centered in the studs when working through what looks like sheetrock. Screws that are too short or small in diameter could give or pull out over time.

[Scott Wigginton]

The one item that was not addressed is the type of bolting or screws used to mount the brackets. That will most likely be the weak link in the system. There is the problem of getting enough screw engagement centered in the studs when working through what looks like sheetrock. Screws that are too short or small in diameter could give or pull out over time.

From their appearance the hangars are not bolted but slide in like these (http://www.leevalley.com/wood/page.aspx?c=1&p=32145&cat=1,43326).

The hangers appear to stick out 1/2" which is probably why Lee Valley and Grizzly recommend using 3 1/2" lags.

Interesting figures on the lags strength, I wouldn't have figured the thinner screws would hold better than the thicker lags. Y'all know a good source to get 'em from?

[Mitchell Andrus]

If you're using some high-strength lags... OK.

But, if only ONE pops a head... the zipper effect will be a-something to watch.
.

[Ken Higginbotham]

I think to be safe you should let me store some of that for you...

:D

[keith ouellette]

I think to be safe you should let me store some of that for you...

:D

Its only white pine (maybe spruce). But it is over 200bf ow white pine.


Chris B. just gave me these calculations...

The withdrawl force for lag bolts is calculated by:
p = 8100 * G ^(3/2) * D ^ (3/4) * L

Where:
p = load (lb)
D = shank dia (in)
G = specific gravity of the wood in use
L = penetration depth (in)

G of spruce is .45
D of 3/8 lag bolt = .265 in
L (assuming 3.5" bolt, 5/8 wall board, .5" on standard) = 2.375"

so...

p = 2100 lbs.

I know I originally said they were 3/8 by 3" lags but they are actually 3 1/2. This looks like some official type stuff so I'm gonna stick with it.

[Terry Brogan]

Iron pipe direct into studs.

[Craig D Peltier]

I have that much on my wall. Its mostly cherry though. My rack is home made , lagbolted to the wall , plywood straps and plywood arms. Design was from a magazine. Its been up for 2 years. Seems fine. Not worried about wall.

[Mark Bolton]

From memory, lags of this size are rated at about 200# in shear (maybe a little less?), so if you have 3 per bracket, you are good for 600#, but that is if all 3" are in the wall. I cannot recall what the pull-out strength is though. This number depends on the screw itself, as well as the species of lumber it is in (SYP is better than SPF for example).

I could be wrong, but I think a 3/8" grade 2 bolt is rated around 800lbs of shear at the full bolt dimension and around 500lbs or so at the root. I cant find the info but I think a common average for 3/8 lags is 200-400lbs pullout per inch embedded.

Mark

[Leo Graywacz]

Looks totally unsafe to me, it'll be falling down any minute. I suggest you take it down immediately and I am willing to store it for you in my wood racks. It'll be safe there. Just don't turn away for to long.http://fototime.com/76D63ADE8141E9C/orig.gif

[Chris Bruno]

Its only white pine (maybe spruce). But it is over 200bf ow white pine.


Chris B. just gave me these calculations...


I wanted to clarify that these calculations are the maximum load possible for those dimensions, etc. There are several deratings that should be applied based on the specific applications and is why the suggested numbers that Mark quoted are generally used. Even at those numbers, Keith ends up with a safety factor of greater than 8 with my estimates of the weight of his wood, which would do very well by me.

-Chris